The use of photodetectors as sensors of fluorescent radiation emitted by an X-ray responsive material are known in the art. By example, U.S. Pat. No. 4,996,413, entitled "Apparatus and Method For Reading Data From an Image Detector" by McDaniel et al., describes an n.times.m array of photodetectors (a non-CCD, MOS-type imager). Image information is read-out by sequentially selecting groups of rows starting with a row near the middle of the array and then sequentially selecting other groups of rows on alternative sides of the array middle. The array is said to be divided into two groups of detector elements in order to decrease an amount of time to read-out the signal from each detector element in the array (col. 4, lines 49-52, col. 5, line 57 to col. 8, line 8). In this system an image processor 28 is said to produce a brightness control signal which is fed to an exposure control circuit 34 to regulate an X-ray tube power supply 16 and thereby the X-ray exposure (col. 3, lines 24-27).
Such MOS-types of photodetector arrays include rather large peripherally-located scan generators and structures which place constraints on the shape that the array can take.
The use of a charge coupled device (CCD) to record light emitted from a phosphor screen in response to X-rays is also known in the art. By example, in U.S. Pat. No. 5,142,557, entitled "CCD And Phosphor Screen Digital Radiology Apparatus And Method For High Resolution Mammography", Toker et al. describe the use of a CCD camera 20 having a cooled CCD array and a MIN-R phosphor screen 4. FIG. 5 shows an embodiment where a fiber optic reducer 45 is placed between the phosphor screen 4 and the CCD camera 20. FIG. 6 shows a parallel CCD array 61 and a CCD serial register 62. During an exposure clocks to the parallel array 61 are stopped, while serial register 62 is clocked and read-out to monitor the accumulated light exposure. A computer 65 generates a signal to terminate the X-ray dose as soon as a certain minimum acceptable threshold dosage is received (col. 9, line 16 to col. 10, line 37). An externally generated signal is required to indicate that the exposure has begun (col. 9, line 67 to col. 10, line 1).
In the approach of Toker et al. the location of the serial CCD register 62 is not specified and, from its connectivity with the parallel array 61 in FIG. 6, would appear to be external to the parallel array as is the case with most if not all CCD image sensors.
For example, it is known that dental X-ray sensors have been constructed with a simple rectangular CCD array having a linear readout register along one edge, although it is not known if any of the edges of such arrays have been beveled, or if the readout register has been employed also for other purposes.
In U.S. Pat. No. 5,331,166, entitled "Dental X-ray Image Detecting Device With an Automatic Exposure Function" by Yamamoto et al., there is described a medical X-ray image detecting device that includes an X-ray intensity detecting element that is located in a casing adjacent to an X-ray image sensor. The image sensor further includes a CCD device located on a ceramic substrate, and glass fiber bundles disposed between the CCD and an X-ray fluorescent element.
In U.S. Pat. No. 5,291,010, entitled "Solid State Imaging Device Having a Chambered (sic, Chamfered) Imaging Device Corner" by Tsuji, there is described a CCD having two corners that are chamfered and that is located within an electronic endoscope.
Other U.S. patents of interest in this area include U.S. Pat. Nos. 4,426,721; 5,113,077; 5,140,162; 5,142,557; 5,187,380; 5,340,988; 4,179,100 and 5,369,281. Also of interest are Japanese Patents 403165291 A; 403189585 A and 405130991 A; European Patents 000574690 A2 and 00429977 A; and German Patent 3522515.